1. Field of the Invention
The invention relates to flow valves. More particularly, the invention relates to valves for use in applications where high purity and low turbulence fluid flow is desirable.
2. Description of the Related Art
In many industrial applications, the control of fluid flow is necessary, and a wide variety of valve designs for performing this control are well known. In some applications, the dispensing of well controlled volumes of pure chemical reagents in liquid or gaseous form is required. Such applications include chemical and pharmaceutical processing, semiconductor manufacture, as well as many others. In these applications, low turbulence and minimal contamination in the fluid distribution process are significant concerns.
Currently available valves, however, generally include internal seals, non-linear flow pathways, and other features that increase the potential for contamination and turbulence. Although a linear fluid path valve without internal seals is described in U.S. Pat. No. 5,848,780 to Miller et al., this valve includes a large number of parts, and requires magnetized metallic elements in the fluid flow stream. Thus, the Miller et al. valve design results in a high manufacturing cost, increased maintenance, and internal components which may be incompatible with the fluid in the valve. Accordingly, what is needed in the art are fluid flow valves which are inexpensive to manufacture, which allow low turbulence flow, and which are less susceptible to leakage or contamination of the flowing fluid.